Filtering attachment for anesthetizing machines



Dec. 31, 1929. J. A. HEIDBRINK 1,741,233

FILTERING ATTACHMENT FOR ANZESTHETIZING MACHINES Filed Aug. 17, 192 4Sheets-Sheet 2 Hel o/br'l'nk.

fitter-mega I n ven for:

Patented Dec. 31, 1929 PATENT OFFICE JAY A. HEIDBRINK, F MINNEAPOLIS,MINNESOTA FILTERING- ATTACHMENT FUR vANJESTHETIZEIIN'G- MACHINESApplication filed August 17, 1927. Serial NO. 213529.

My invention relates to filtering attachments for aneesthetizingmachines for the purpose of filtering from the gas exhaled by thepatient, impurities such as carbon dioXid thrown off with the exhaledgas as waste products of body metabolism. The gas thus purified may bebreathed over again by the patient and repeatedly purified and againbreathed in. Since anaesthetic gases are expensive economy in the usethereof is desirable. In the manner above stated, two or three gallonsof gas such as nitrous oxid which is unchanged by its excursion throughthe body, may he used to produce anaesthesia for an hour or more. It iscommon practice among anaesthetists, even with a filter not in use, tosupply the patient with less volume of gas than is sufficient to supplybreathing so that there will be some rebreathing of ex haled gascontaining carbon dioxid, the object being to stimulate respiration withthe carbon dioxid thus retained, it being well known that carbon dioxidis a respiratory stimulant. In filtering devices now used, all

the exhaled gas must pass through the filter and all carbon dioxid isremoved so that there is no rebreathing of carbon dioxid. An object ofmy invention is to provide a device that will function in connectionwith rebreathing for removing a predetermined amount of carbon dioxidfrom the gas exhaled by the patient :before the gas is again inhaled; Itis well known as above stated that in administering gas anaesthetics itis usually desirable to supply some carbon dioxid to the patient inorder to stimulate respiration. Since carbon dioxid is expelled from thelungs of the patient, rebreathrng,

as commonly employed provides :a means for 4D furnishing the patientwith carbon dioxid. I have found, however, that under differentconditions, and for different patients, it IS "extremely de'si r ableitd :be :able to readily vary the amount of carbon dioxid which is supgplied and some nes it may even be advisable to memoveithe carbon dioxidas fast as it is expelled from the liimgs before the "gas is rebreathed.I Thavegtherefore, devised the attac'hment herein disclosed embodying afilter $0 for the :carbondioxid which may be quickly set for removingamounts of carbon dioxid from theexhaled gas varying from zero up tosubstantially complete removal. Many anaesthetists introduce carbonrdioxid in definite amounts run from separate tanks to the re- 5breathing bag for stimulating the ,patients respiration. Therefore,another object of my invention is to be able to admit .to therebreathing bag, carbon idioxid and have it pass to the patient beforeit comes into contact with the purifying material which would absorb thecarbon dioxid. Another object of my invention is to provide means forquickly changing from purifying the gas as above described to supplyingthe patient with a continuous volume of fresh gas from the anaesthetizerand vice versa.

The full objects and advantages of my invention will appear .inconnection with the detailed description thereof and the novel featuresof inventive idea will be particularly pointed out in the claim.

In the accompanying drawings which i1- lustrateione form in which anyinvention may be embodied,-

Fig. l is a top plan view of the device attached to an anaesthetizingmachine. Fig. 2 is a fragmentary View in section on the line 22 of Fig.5. Fig. 3 is a View in section on the line 33 of Fig. 5. Fig. 4 is aView in section on the line 4-4 of Fig. '3. Fig. '5 is a View insectionon the line 5-5 of Figs. 3 and 7. Fig. 6 is .a view in section on the,line 6-6 of Figs. '8 and 7. Fig. 7 is a view in-section on the line 7-7of Fig. 3. Fig. 8 is 'a view similar to Fig. .5 but showing therotatable valve turned into a different position.

Referring to the drawings, and first, more particularly, to Fig. .1, mydevice is shown connected to a well-known form of anaesthetizing machinein which there are a pair of arms 10 and .12 supported in suitablemanner and which carry .cross arms :14 and 16, respectively. The'ends.of these crossarms are provided with yokes 18 within which the heads 20of gas containers are secured by screws 22. In the particular formshown, the gas containers on .one side are intended forhold-ingoxygenand the ones on the other side for holding ananaesthetizing gas such as nitrous oxid. The cross arms 14 and 16contain passageways with which the gas containers are adapted to beplaced in connection in the usual way. These passageways are providedwith pressure control devices 24 of well-known construction which areprovided with regulating screws 26. The gases mixed in regulatedquantities pass to a valve casing 28 containing a rotatable valveoperating by a handle 30 in the usual manner. Extending forwardly fromthe valve casing is a hollow projection 32 to which my attachment isapplied, the end of this projection being threaded to receive a couplingdevice 34 rotatably held upon one end of a tubular member 36 of acasting designated in general by the numeral 37. The direct passagethrough the tubular member 36 is blocked by by a screw plug 38 so as toform two separated passageways 40 and 42. The passageway 40 communicatesthrough a lateral port 44 with a passageway 46 formed in a member 48projecting out from the side of the member 36. The passageway 46 at itsfront discharges into a vertical passageway 50 having a port 2' at itsbottom, as shown in Fig. 7 which opens into the interior of a hollowmember 54 converging to form a neck 56 to which a rebreathing bag 58 issecured. Above the member 54 the casting at the left-hand side isprovided with a chamber 60 having an opening 62 adapted to communicatewith the interior of the hollow member 54, this opening being controlledby an upwardly-opening disc valve 64 of light weight. The chamber 60 isclosed at the top by a screw plug 66 which carries downwardly-extendingstrips 68 to prevent the disc 64 from being displaced too far from itsseat. The middle portion of the casting contains a verticaldownwardly-tapering hole in which a rotatable plug valve 7 0 is fitted.This valve has an upwardly-projecting stem 72 to which a handle 74 issecured. The lower portion of the valve is hollowed to produce acompartment 7 6, which opens at the bottom into the hollow member 54.The compartment 7 6 is provided with a lateral port 7 8 which is adaptedto register with a port with which the chamber 60 is provided, as bestshown in Fig. 6. The upper portion of the valve 70 is provided with anangular passageway having two portions extending at right angles to eachother to form two ports 82 and 84 which are spaced above the port 78 butangularly disposed with relation thereto, as will be evident from Fig.8. At the side of the casting opposite the chamber 60 the casting isprovided with a chamber 86, as best shown in Fig. 7, having an opening88 at its bot tom controlled by an upwardly-opening disc valve 90 oflight weight. The chamber 80 is closed at the top by a screw plug 92which carries downwardly-extending strips 94 to prevent the disc 90 frombeing displaced too far from its seat. The port 84, as will be obviousfrom Figs. 5 and 8, is adapted to register with a passageway 96communicating with the chamaer 86, while the port 82 is adapted toregister with the passageway 42 previously referred to. he passageway 42has a port 98 in its lower side which opens into a cylinder 100extending down from the upper portion of the casting. The lower end ofthis cylinder is provided with a screw closure 102, on removal ofwhichaccess may be had to the interior of the cylinder. This cylindercontains a cup 104 having a screenlike bottom 106 below which are-feet108 which support the screen above the closure 102 so that free passagefor gas may be had from the cup through a port 110 into the hollowmember 54 and into the rebreathing bag 58. The cup 104 is provided forcontaining filtering material which will absorb carbon dioxid. Amaterial suitable for this purpose consists of what is commonly known assodalime, which is in medium sized crystals. This material is indicatedby the letter C in Fig. 3. The chamber 60 communicates with aforwardly-extending nipple 112, while below the level of the disc valve90 there is a forwardly-extending nipple 113 in communication with theopening 88. Tubes 116 and 118 are fitted on the nipples 112 and 114,respectively, and these tubes, at their forward ends, are united andattached to an inhaler 120, which may be of well-known construction.Secured to the valve stem 72in line with the handle 74, there is apointer 122 which, upon turning of the valve 70, is caused to registerwith graduations124 on a dial, as shown in Fig. 1. In this figure, whenthe pointer registers with the left-hand graduation, the passage fromthe inhaler to the filtering material is entirely open while directpassage from the inhaler to the rebreathing bag is entirely closed.lVhen the pointer is in registration with the right-hand graduation, thepassage from the inhaler to the filtering material is entirely shut,while direct passage from the inhaler to the rebreathing bag is entirelyopen. In the latter case'the machine functions as though the filter isnot present. The dial may be accurately graduated by setting the valve70 so that the gas is divided into two equal parts and then marking theposition of the pointer on the dial as half way graduation. The othergradua- M tions may be similarly determined in accurate manner.

The operation and advantages of my invention will now be readilyunderstood. Assuming that the pointer is in the midway position, thevalve 7 0 occupies the position shown in Fig. 8. When the patient nowexhales, half of the exhaled gas has a tendency to pass from the inhalerthrough the tube 118 and nipple 114, then through the opening 88 pastthe Valve 90 and through the ports 84 and 82 into the passageway 42 anddown through the port 98 to the filtering material C, which removes thecarbon dioxid. The gas thus treated continues on into the rebreathingbag. The other half of the exhaled gas has a tendency to pass throughthe tube 116 and nipple 112, then through the ports 80 and 78 to thechamber 76 in the lower portion of the valve and down into therebreathing bag, where it mingles with the portion from which the carbondioxid has just been removed. When the patient inhales, this valve 90closes and prevents gas being drawn back through the filtering materialand through the tube 118, The disc valve 64, however, will open so as topermit free flow of the mixed gas .from the rebreathing bag through thetube 116 to the inhaler. If the rotary valve 70 be turned so as to bringthe pointer into the open position shown in Fig. 1, then this valve willoccupy the position shown in Figs. 5 and 6, so that there is a free openpassage for the exhaled gas through the ports 84 and 82, as will appearfrom Fig. 5. As will be apparent from Fig. 6, the port 78 at this timeis en-' tirely out of register with the port 80, so that none of theexhaled gas can pass back directly to the bag. In this position, therefore, all of the exhaled gas which is forced into backward position issubjected to the action of the filtering medium before reach ing thebag. When the patient now inhales, the gas from the bag will go past thedisc valve ti l-and through the tube 116 to the inhaler. Assuming nowthat the rotary valve 70 is turned so as to bring the pointer into theshut position indicated at the right in Fig. 1, it will be apparent froman inspection of Fig. 8 that port 82 is entirely shut off fromcommunication with the passageway 42. The port 7 8 will, however, bebrought into complete registration with the port 80, so that when thepatient exhales there is a tendency to force all of the exhaled gasdirectly back into the rebreathing bag. With this setting of the valvethere is no filtering of the exhaled gas. It is obvious that by placingthe pointer on the proper graduation marks various proportionate amountsof the exhaled gas will be filtered, such as one-quarter andthree-quarters.

I claim:

A filtering attachment for anaesthetizing machines comprising aninhaler, a valve casing, two tubes connecting said casing directly withsaid inhaler, a hollow member extending downwardly from said valvecasing, a rebreathing bag secured to the lower end of said hollowmember, a receptacle secured at the rear of said hollow membercontaining covering material for absorbing carbon dioxid, the bottom ofsaid receptacle having an opening'into said hollow member, a rotatablevalve in said casing, said valve having a passageway cooperating withone of said tubes for passing variable proportions of the exhaled gas tosaid filtering material before reaching said bag and said valve having asecond passageway cooperating with the other of said tubes for passingthe rest of the exhaled gas directly to said bag, and a tubular memberextending rearwardly from said valve casing for connection with sourcesof gas supply, said tubular member having two compartments, one of whichprovides a passageway directly from the source of supply into saiddownwardly extending member and the other of which provides a passagewayfrom said valve to the top of said filtering receptacle.

In testimony whereof I hereunto aflix my signature.

JAY A. HEIDBRINK.

